This section introduces information from the art that may be related to or provide context for some aspects of the techniques described herein and/or claimed below. This information is background facilitating a better understanding of that which is disclosed herein. Such background may include a discussion of “related” art. That such art is related in no way implies that it is also “prior” art. The related art may or may not be prior art. The discussion is to be read in this light, and not as admissions of prior art.
Solutions comprising tert-butyl hydroperoxide (also referred to herein as “TBHP”) in the presence of tert-butyl alcohol (“TBA”) have been formed in the past and have utility in various chemical reactions, including epoxidation reactions. TBHP concentrations in such solutions in some instances have been increased to 65 wt % or higher via a vacuum distillation process that lowers the concentration of TBHP in the vapor phase of the distillation column of the reactor, in order to avoid the presence of a flammable mixture in the distillation column. Non-limiting examples of such a vacuum distillation process to achieve 65 wt % TBHP solution can be found in U.S. Pat. No. 5,104,493. But previous TBHP solution formation processes have drawbacks, including yield-lowering levels of impurities and inefficient loss of TBHP in the distillation overhead streams. When a TBHP in TBA solution with yield-lowering levels of impurities is employed in epoxidation of propylene to produce propylene oxide and TBA, the impurities result in a lower yield of propylene oxide. Complicating the situation is the fact that epoxidation reactions carried out by direct injection of solutions with TBHP in TBA concentrations of 65 wt % or higher to an epoxidation reactor are highly exothermic and present operational risks associated with runaway reactions.